Configuring Security Policy
Security is an important consideration when building applications. The common language runtime grants varying levels of trust to code based on certain attributes, called evidence, that the code possesses. When the runtime establishes that code has a certain level of trust, it allows the code to access protected resources appropriate to that level of trust. For example, by default, a .NET Framework application that runs from the Internet does not have the same level of trust as a .NET Framework application that runs from the local computer. An application running from the local computer can access resources such as the file system, but an application running from the Internet cannot.
The default security policy provides adequate security for your computer, and you should change it only when necessary. Before configuring security policy, you should become familiar with the concepts described in Security Policy Management. Use the .NET Framework Configuration tool (Mscorcfg.msc) to change security policy. If you want to write a batch script to configure security policy, use the Code Access Security Policy tool (Caspol.exe).